Automatic identification technology is used to help identify persons or objects and automatically provide data relating to the persons or objects. Typically, authenticated or certified documents are presented as a basis for granting services or benefits to an individual, for example when using passports or visas from state, local, and federal government agencies. RFID tags or embedded devices may be used to certify legal documents or to assure that a document is not counterfeit such as the Common Access Card (CAC) used by the U.S. Department of Defense.
One early technology was the bar code serial number system. However, a bar code cannot store detailed information that relates to an individual person or item, such as an expiration date (for example, on a food item or a passport visa). Another identification technology, including RFID devices, RFID circuits, and RFID tags, is presently manufactured and used to track a variety of items and materials. RFID devices are also used to track transactions when they are embedded in, for example, credit cards. Contactless smart card technology is used in applications that need to protect personal information and/or deliver secure transactions, such as transit fare payment cards, government and corporate identification cards, electronic passports and visas, and financial payment cards. Contactless smart card technology is available in a variety of forms as plastic cards, watches, key fobs, documents, and other handheld devices, for example, built into mobile phones or personal digital assistants.
Emerging RFID technology employs a radio frequency (RF) wireless or contactless link and an RFID device may include an embedded computer chip. RFID technology allows persons or objects to be identified and allows detailed information to be stored within an individual RFID device. For example, an implementation may include a secure microcontroller embedded in a page or cover of an e-passport. Other examples include driver's licenses, birth certificates, and marriage certificates. The owner's personal information, such as an encoded cryptographically signed copy of a photograph, signature, fingerprints, and other biometrics data, may be securely stored in an RFID device. Communication with a machine-readable passport may be contactless. The ISO/IEC 14443 standard, which is currently applied in the credit card and payments industry, may be used in authorizing documents such as an e-passport. Generally, a variety of communication channels or frequencies may be used, depending on the data transfer rate requirements, and other factors.
An RFID may have a battery included in the device, or may be passive, having a contactless power source driven by a magnetic field from an RFID reader. Generally, an RFID device, having no batteries or power source of its own, relies on getting its power from an RFID reader's RF signal to operate. When the RFID device is brought into an electromagnetic field of the reader, the IC chip in the RFID device powers on. Once the IC chip is powered on, a wireless communication protocol is initiated and established between the card and the reader for data transfers. The new e-passports embed a type of smart card technology, which is not the same as simpler RFID tags being used to track products. An RFID tag will generally send only the ID number stored in the RFID tag. Contactless smart card technology, based on the ISO/IEC 14443 specification, powers on when a low power radio frequency signal of 13.56 MHz is applied within a few inches of the RFID device. Other frequencies may be used, for example, a 125 KHz channel, a 134 KHz channel, or using a 915 MHz carrier.
Smart card technology defines communication protocols, and the RFID device may receive commands and update the information stored in the RFID device. Encryption and security certifications are generally used in applications such as an e-passport to resist security attacks, and some applications require up to 10 years or more of error-free operation. If a contactless device is attached on an ID document, it generally remains operational for the entire life of the document. For example, an e-passport may contain several operational contactless RFID devices corresponding with visas for several countries. A single document requiring multiple certifications may contain several RFID devices. Currently, if a contactless RFID device is attached to a document, the RFID device remains active for the entire life of the document.
Referring to FIG. 1, a prior art RFID device 100 contains a receiving antenna element 101, an oscillator circuit 102, a power circuit 103, a clock circuit 104, a control circuit 105, and transmitting or send circuits 106 and a sending antenna 107. The oscillator circuit 102 may be comprised of RF matching passive components such as an inductor and capacitor. An alternating current (AC) signal, received on the antenna 101, is rectified by the power circuit 103 to produce a direct (DC) current source to provide a voltage source to power the other circuits in the RFID device 100. A clock (extraction) circuit 104 extracts a clock or timing signal that is used for clocking components and signals used by the RFID device 100. The control circuit 105 may control the send circuits 106 to send stored data (identification) information to an RFID reader (not shown). Other circuits contained in the RFID device 100 may include memory containing ID information, interface circuits, and transmission circuits. Generally, the circuits will read an identification number, identification code, or other information stored in the RFID device, and then transmit the stored ID information to the RFID reader.
U.S. Pat. No. 6,147,605 to Vega et al. entitled “Method And Apparatus For An Optimized Circuit For An Electrostatic Radio Frequency Identification Tag” discusses an oscillator to an RFID tag. However, Vega has a disadvantage of not being able to fully deactivate the device. U.S. Pat. No. 6,476,708 to Johnson entitled “Detection Of An RFID Device By An RF Reader Unit Operating In A Reduced Power State” discusses an excitation signal generator and an activation circuit in an RFID tag. A flip-flop switch toggles the RF transponder between a reduced and increased power state. However, Johnson suffers a disadvantage of having no means to permanently deactivate the device since the flip-flop state cannot be maintained without a power signal.
It is desirable to, for example, have a contactless device that may be disabled or deactivated, for example, a visa that is not valid or has expired in an e-passport.